Wildlife Deterrence System Arranged in Wind Turbine Blade

ABSTRACT

Systems and methods are disclosed for deterring wildlife, such as bats and birds, from drawing too proximate to an operating wind turbine. Wildlife species may be sensitive to transmitted frequencies, such as ultrasonic frequencies above the range of human hearing. For example, bats may avoid areas where ultrasonic frequencies are being emitted, either because the emitted ultrasonic frequency interferes with the echolocation of the bat, or because encountering the ultrasonic frequency is uncomfortable for the bat. In some aspects, acoustic transmitters may be arranged along a length of a blade of a wind turbine. A controller may direct the acoustical transmitters to transmit signals having ultrasonic frequencies to deter wildlife encounters. The controller may direct the transmitters to transmit only during periods where wildlife encounters are likely to occur (e.g. at night, during migration seasons, during favorable weather conditions, or the like).

TECHNICAL FIELD

Aspects described herein generally relate to the production, generation,and/or harnessing of wind energy by increasing the reliability andoperational uptime of wind turbines or other similar devices.

BACKGROUND

Wind turbines are known. They are renewable energy devices that mayprovide energy with minimal to zero environmental effects. Global energydemand continues to increase as a result of continued industrializationand population increase. Likewise, environmental concerns also continueto play more significant roles in economies and industries across theglobe including concerns relating to air quality, draining of naturalresources, and climate change, to name a few. Accordingly, innovationrelating to renewable energy methods and devices and wind turbines inparticular is of significant interest, importance and attention. Windturbines and methods of operating, maintaining, controlling andotherwise using wind turbines are of significant interest and researchas they relate to energy production and consumption as well as thepreservation of the environment and other natural resources. Windturbines may be utilized in varied climates and are exposed to variouselements including extreme temperatures, precipitation including snow,sleet, freezing rain, and hail, and other environmental factors.

BRIEF SUMMARY

A development with the deployment of wind turbines has been theireffects on wildlife, especially bats, in the areas of deployment. Alarge number of bats have been killed by wind turbine facilities in theUS and Canada over the period from 2001-2010, with estimates rangingfrom 650,000 to more than 1,300,000 fatalities. Given that in some areaswind capacity has doubled over the period from 2010-2014, the challengeof mitigating fatal interaction of bats with wind turbines is becomingincreasingly important.

In view of the foregoing, aspects directed herein are directed to newand retrofitted wind turbines which include acoustical transmissiondevices, such as ultrasonic frequency generating transmission devices.Due to their position in-blade, the transmitters can project through anarea beyond the blade tip, thus enabling a system that provides acousticflight deterrent coverage that includes both the rotor area of the windturbine and a buffer zone. According to some aspects descried herein, acontroller may be provided for controlling various characteristics ofthe transmitters, such as when the transmitters are enabled or disabled,the transmission frequencies, the transmission power, or the like. Forexample, the transmitters may only be enabled at night or during awildlife migratory period.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features, and wherein:

FIG. 1 is an illustrative front perspective view of a wind turbine.

FIG. 2 is an illustrative partially schematic view of a wind turbine.

FIG. 3 is an illustrative schematic view of an acoustical transmissionsystem of a wind turbine.

FIG. 4 is an illustrative exploded view of an acoustical device locatedin a wind turbine.

FIG. 5 is an exemplary depiction of a wind turbine operating inaccordance with one or more aspects described herein.

FIG. 6 is an illustrative view of aspects of a controller.

DETAILED DESCRIPTION

In the following description of the various embodiments, reference ismade to the accompanying drawings, which form a part hereof, and inwhich is shown by way of illustration various embodiments in which theinvention may be practiced. It is to be understood that otherembodiments may be utilized and structural and functional modificationsmay be made without departing from the scope of the present invention.

A brief discussion of wind turbine operation follows. Wind turbinescreate power proportional to the swept area of their blades. Increasingthe length of a wind turbine's blades increases the swept area.Accordingly, more power can be produced or captured. A wind turbine'sgenerator, gears, bearings, and support structure are typically designedaround the expected wind load and power production characteristics. Atlow wind speeds very long blades are desirable to get as much power aspossible out of the available wind. However, wildlife may be present atlow wind speeds, and increasing blade length will result in an increasedarea for wildlife to come into contact with the blades.

Curtailment of a wind turbine may occur when there is wind capable ofproducing energy, but the wind turbine does not output power or does notproduce the expected amount of power. Reasons for curtailment may vary.For example, operation of the wind turbine may result in an over-loadingof a transmission line. Shutdown costs and cost variability of otherplants present in the power generating network may factor intocurtailment of a wind turbine or wind farm. Curtailment may also occurbecause of potential impact to wildlife in the area, such as birds inmigration or bats.

Wind power cost is a function of productivity and is driven by the highfixed costs of wind turbine projects. The higher the capacity factor(CF) or utilization of turbines, the lower the cost per unit for eachkWh generated. A reduction in forced curtailments due to wildlifeactivity may therefore reduce costs to ratepayers. Additionally, byenabling the deployment of a more-productive new generation of windturbines with larger wind turbine blades, wildlife deterrence mayfurther reduce ratepayer costs.

Wildlife deterrence may also serve to improve system reliability. Whenfewer turbines are affected by forced curtailments, more turbines areoperating and producing energy. This higher utilization of capacityimproves the capacity value of wind farms. Inefficient peak generators,such as simple cycle gas plants, that only run to balance out variationsin intermittent wind generation may need to operate less. This may makeadditional peak generation (spinning reserve) available to improvereliability. Higher utilization may also improve reliability byimproving the predictability and efficiency of the electricitytransmission system.

As aspects of the disclosure may be retrofitted into existing turbinesand installed in new wind turbines, aspects described herein maymaterially overcome a significant challenge of the wind power industryby reducing wildlife fatalities and injuries from turbine strikes.

FIG. 1 is a front perspective view of a wind turbine 10 according tosome aspects of the disclosure. Wind turbine 10, which is mounted atop atower 9 secured in a foundation 8, includes a rotor 11 and a nacelle 12.Nacelle 12 may house a generator that is rotationally coupled by a drivetrain to a hub 14 of rotor 11. The drive train and generator are notvisible in FIG. 1. Nacelle 12 may also house one or more controllerssuch as are described below.

In addition to hub 14, rotor 11 includes three blades 20, 23, and 26. Inother embodiments, a wind turbine rotor may include more or fewerblades. Each of blades 20, 23, and 26 may be coupled to hub 14 by aconventional pitch actuator that allows the pitch of the rotor blade tobe varied. In one arrangement, blades 20, 23, and 26 may be fixed lengthrotor blades having respective root portions 21, 24, and 27 andrespective tip portions 22, 25 and 28. In other embodiments, each ofblades 20, 23, and 26 may be variable length blades having blade tipsthat can extend and retract.

The rotor blades as shown in FIG. 1 may be formed of any of a variety ofsuitable materials known to be used in the art. For example, rotorblades on large wind turbines are often made of glass fiber reinforcedplastics (GRP), i.e. glass fiber reinforced polyester or epoxy.Reinforcing materials such as carbon fiber or aramid may also be used inrotor blades in certain instances. Steel and aluminum alloys may also beused for rotor blades especially small wind turbines. Wood, wood-epoxyor wood-fiber-epoxy composites also may be utilized. Various othermaterials may be used for the rotor blades as is known in the art.

Also present in the system of FIG. 1 is a controller 50. Controller 50may control acoustical transmissions from the transmitters arrangedalong the blades of the wind turbine. The acoustic transmissioncontroller 50, or components or subcomponents thereof, may be housed inany of the turbine blades 20, in the hub 14, nacelle 12, elsewhere inthe turbine 10, or not located in the turbine at all (e.g. at a locationremote from the wind turbine). Additionally or alternatively, one ormore components or modules of the controller 50 may be housed in each ofthe blades of the wind turbine and may be operably coupled to furthercomponents housed in the wind turbine of which there may be only one ofin each wind turbine.

Regarding wildlife deterrence, it is generally understood that bats usean echolocation mechanism to perceive their surroundings. Bats listen tofeatures of echoes resulting from the transmission of high-frequencyvocal signals, which are reflected from targets in the path of the soundwave. Bats generally have developed extremely sensitive hearing organsto listen for potentially faint echoes. The deployment of broadbandultrasonic noise may hinder echolocation, confusing a bat and resultingin its avoidance of the area where the noise is occurring or emanating,thus acting as a repellent to bat activity. Ultrasonic noise may alsojam echolocation abilities, and a repellant effect from the deploymentof ultrasonic noise producing devices may result from bat sensitivity tosuch ultrasonic noise. Ultimately, the bat may be encouraged to seek anarea or path where ultrasonic noise is not present.

FIG. 2 is a partially schematic front view of wind turbine 10 showingadditional details of blades 20, 23, and 26. Blade 20 includes multipletransmitters 30(1) through 30(7). Those transmitters, which may beultrasonic transmitters, may be referenced collectively and/orgenerically using the same reference number 30, but without an appendedparenthetical. A similar convention will be followed with regard tocomponents of ultrasonic transmitters 30. Each transmitter 30 has alocation on blade 20 that has a distance R from the root of blade 20.For example, transmitter 30(1) is displaced from the root of blade 20 bya distance R1. Although FIG. 2 shows blade 20 with seven transmitters30, this is only one example. In other embodiments, a blade may havemore or fewer transmitters. The positioning of transmitters 30 is alsomerely one example. In other embodiments, transmitters may be placed atother locations on a blade. In some aspects, the transmitters may bespaced at a distance of 5-20 meters from each other, for example, atevery 7 meters. As will be discussed below, an acoustical model may bedeveloped for determining a more precise spacing, as the placement ofthe transmitters along the blade may be variable by employment of amodular socket system detailed below with respect to FIGS. 3 and 4.

Blades 23 and 26 may be substantially identical to blade 20. Inparticular, each of blades 23 and 26 similarly includes transmitters.Blade 23 includes seven transmitters 33(1) through 33(7). Transmitters33 may be similar to transmitters 30 and may be positioned on blade 23in a manner similar to the manner in which transmitters 30 arepositioned in blade 20. Blade 26 includes seven transmitters 36(1)through 36(7). Transmitters 36 may also be similar to transmitters 30and may be positioned on blade 26 in a manner similar to the manner inwhich transmitters 30 are positioned in blade 20.

FIG. 3 provides an illustrative schematic detailing one potentialarrangement of a transmitter 30 in a blade of a wind turbine.Transmitter 30 may be any device capable of producing an acousticalsignal having a frequency. In some aspects, transmitter 30 may be apiezoelectric disk capable of producing multiple acoustical signals atdifferent frequencies simultaneously. Transmitter 30 may be arranged,located, constructed, or the like in a housing for placement in a socket45 in a blade 20. The socket housing may be bonded to the wind turbineblade skin using an adhesive, and may be located in either the suctionside or the pressure side of the blade airfoil. The housing, may becylindrical in shape, or may have any other shape or form, such as thatof a cone, cuboid, rectangular prism, triangular prism, or the like.Similarly, the socket may be designed to have a shape designed toreceive the shape chosen for the transmitter housing. In someembodiments, the housing may be sized and shaped to fit a socket forother transmitters, sensors, or the like. For example, in some aspects,seven sockets may be installed along the length of the blade.Transmitters 30 may be installed in every socket, every other socket, orevery third socket (as examples). The remaining sockets may receivesensors, such as pressure sensors, or other transmitters, such as lightor signal transmitters.

FIG. 4 also provides an exemplary illustration of the relationshipbetween the housing in which transmitter 30 is arranged and the socket45. In some arrangements, cabling through the hollow portions of theblade 20 may be fed through the socket 45 and attached to components ofthe transmitter 30. In some aspects, this may include power and controlcable 47 and ground conductor 49. Ground conductor 49 may be used todissipate surge currents which may develop on a surface of the airfoil,for example static charge or lightning strikes. Depending on factorssuch as cost, likelihood of charge build-up, or the like, groundconductor 49 might not be used.

Power and control cable 47 may transmit a bi-directional oruni-directional analog or digital signal which may be used to powerand/or control the transmitter. In some arrangements, an alternativemethod of wiring the transmitter may be utilized where separate powerwires and control wires are used. As discussed more fully below, in somearrangements, control of the transmitter may be performed viatransmission of a wireless control signal received by a wirelesstransceiver of the transmitter. Accordingly, in some aspects a controlsignal transmitted via control cable 47 might not be present and may beoptional. In some aspects, some control signals may be transmittedwirelessly and others may be transmitted via power and control cable 47.

With reference to both FIG. 3 and FIG. 4, in some aspects a bayonetmount or bayonet connector may be provided by arranging cylindrical andradial male pins 43 on the socket 45, and arranging corresponding femalereceptor slots 41 on the transmitter housing. Other mounting orconnection mechanisms are within the scope of the present disclosure.

The operation of wind turbines may include monitoring systems and/ordevices to monitor among other characteristics stresses, air pressures,energy production, wind speed, rotation speed and various othercharacteristics well known in the art. The pressure on the surface ofthe wind turbine blades is a characteristic that is typically monitoredto prevent damage or destruction to wind turbine blades due toenvironmental effects including wind speeds at extremes and othernatural effects that act on the wind turbine blades during operation.Wind turbines may be equipped with sensing and monitoring systems toprovide data and feedback regarding the operation of the wind turbine.This data and feedback may provide insight into the state of the windturbine and the various stresses the wind turbine may be operating underat certain points in time.

The conditions on the surface of wind turbine blades provide insightinto the forces being applied on the blade and provide insight andfacilitate prediction of potential failures and enable entities andpersonnel controlling the operation of wind turbines to alter theparticular operation to prevent damage, fatigue or failure. To determineconditions locally at the wind turbine, sensing systems includingsensors may be housed in the turbine blade and the remainder of the windturbine. In certain instances the sensing components may be included insockets, such as sockets 45, on the surface of the wind turbine blade.These systems and sockets may begin to fail to operate correctly as theymay become clogged including potentially being covered with ice or otherdebris. Likewise, transmitters 30 may reduce in transmission efficacy orefficiency if covered with ice or other debris.

As such, the present system in various arrangements may be configured todetect failure of transmitting and sensing components, and be able toreact to free debris or to heat ice so as to permit the sensing andacoustical transmitting components to resume normal operation and toagain provide feedback and data to the system for optimal acousticaltransmission.

For example, in various arrangements the disclosed system is configuredto be able to detect failed or improper readings from componentsutilized for determining proper operating conditions. The system may beconfigured to provide removal of moisture, debris and ice from socketsin a wind turbine using air including pressurized air, heating elementsand like elements as understood by one skilled in the art. For example,in at least one configuration a resistive heating element is coiledaround a socket so as to prevent ice formation. The resistive heatingelement may serve multiple purposes including melting ice anddetermining temperature. The system may be configured to also be able totake actions to remedy the improper conditions. For example, upon adetermination of failed or improper readings the system may be able totake action by supplying high pressure air to sockets to dislodge debristhat may be preventing proper operation of the sockets and other sensingcomponents. Likewise, the system may also or alternatively be configuredto heat ice that may have formed over sockets on the turbine blade so asto fix errors or improper operation and return the system to properfunctioning and operation. As such, the system may be configured toperform purging and/or deicing utilizing high pressure air and/or heatsupplied from a heater to eradicate moisture, ice, debris and otherproblematic foreign objects that may obstruct sensing, monitoring,operation or the like with respect to wind turbines and bladesthemselves.

In some aspects, a controller local to one or more wind turbines mayreceive instructions or signals from a master controller, potentiallylocated remotely and operable to control transmissions emanating from aplurality of transmitters at a plurality of wind turbines. For example,there may be only a single controller in the hub of a wind turbine,being operably coupled to the transmitters 40 located along the lengthof each blade. The single controller may receive signals or instructionsfrom a main controller located elsewhere.

In some arrangements, there may be multiple controllers, or componentsor subcomponents of a single controller, each controlling a subset ofthe transmitters of a single wind turbine. For example, there may be onecontroller per blade such that each transmitter of a first blade iscontrolled by a first controller and each transmitter of a second bladeis controlled by a second controller. Alternatively, there may be onecontroller per transmission frequency, such that transmitters of a firstgrouping (which may be located on any of the blades of the wind turbine)transmit at a first frequency, and transmitters of a second grouping(again, which may be located on one or more of the blades of the windturbine) may transmit at a second frequency. Other groupings, both oftransmitters of a single wind turbine and transmitters of multiple windturbines, are possible and within the scope of the disclosure.

The controller may have the ability to control the transmissionfrequency for one or more of the transmitters. As may be seen in TABLE1, various bat species may transmit sounds in a frequency range of 15kilohertz (kHz) to 125 kHz. It is noted that at the low end of therange, the emitted sound from the bat may be audible to humans, withultrasonic frequencies typically defined as those in excess of 20 kHz.Accordingly, although potentially referred to herein as “ultrasonic”transmitters, in some aspects the acoustical transmitters may transmitsignals at frequencies which are audible to humans.

TABLE 1 Bat Species Transmission Frequencies Greater horseshoe bat    83kHz Lesser horseshoe bat 95-125 kHz  Whiskered bat 30-80 kHz Natterer'sbat 30-80 kHz Dauberton's bat 30-80 kHz Greater mouse-eared bat 30-70kHz Bechstein's bat 30-80 kHz Common Pipistrelle 40-45 kHz Serotine bat28-80 kHz Common Noctule 15-50 kHz Barbastelle 30-70 kHz Brownlong-eared bat 15-50 kHz Grey long-eared bat 15-50 kHz

The controller may have the ability to activate the system duringperiods with bat activity. Bats are typically only active duringnocturnal hours, generally from dusk to dawn. The controller mayactivate the transmitters only during these hours. As another example,bats are sensitive to temperature, wind, and precipitation, and thecontroller may receive weather data as an input and make a determinationas to whether activation of the ultrasonic transmitters is warranted. Asanother example, bat species may be migratory, and the ultrasonictransmitters may activate during a migratory season. As another example,the controller may receive a signal from a device, individual, ororganization responsible for providing an indication that wildlife arelikely to be present in the vicinity of the wind turbine. This may be aproximity sensor, a bat monitoring organization, or an individual who istasked with visually determining whether wildlife are near the windturbine.

The controller may have other abilities in addition to or in thealternative to those discussed above. The controller may operate tocontrol the transmission frequency of one or more transmitters so thatthe perceived frequency of signals arriving or converging at a point inspace away from the transmitter is at or near a desired frequency. Forexample, the blades on which the transmitter is located may be rotating,and various acoustical effects, such as the Doppler effect, may create aperceived frequency higher or lower than the transmitted frequency atsome distance from the wind turbine. A signal emanating from atransmitter on a blade drawing nearer to a point in space may beperceived at a higher frequency, and a signal emanating from atransmitter on a blade moving away from the point in space may beperceived at a lower frequency.

FIG. 5 illustrates an exemplary scenario in which a variable frequencycontrol may be used. A bat 60 may have an airspeed of 15 meters persecond, and may require approximately one second of time to react to aperceived sound and divert or change its flight path. Deterring bat 60from potential injury or death from impact with wind turbine 10 mayrequire, therefore, that sound waves 70, which may be ultrasonic soundwaves, have a deterrent effect at approximately 15 meters from theblades of the wind turbine. As discussed above, a controller (not shownin FIG. 5) may control one or more transmitters on the blades of windturbine 10 so that at a location of the bat greater than or equal to thesafe distance of 15 meters, the bat perceives a deterring frequency.This deterring frequency may be higher or lower than the frequency ofthe signals transmitted by the transmitters of wind turbine 10. In someinstances, the frequency of the signals transmitted by the transmittersmay not be a deterring frequency when transmitted.

As discussed above, each transmitter may be capable of producing signalshaving frequencies across a range of potential frequencies. Thecontroller may operate to vary the frequency of the signal produced atone or more transmitters, by referencing (for example) the speed ofrotation of the blade. This may result in a smaller range of perceivedfrequencies at the point in space. Another characteristic which may beused by the controller to control transmission frequency may be thenumber of blades which have transmitters. For example, propagatingsignals from transmitters on multiple blades may add or subtract fromeach other as they travel through air. The controller may control one ormore of the transmitters to enhance or reduce the signal addition orsubtraction.

Another control strategy may be to stagger transmissions from one ormore transmitters, for example enabling transmission of the acousticalsignal when the blade is located at one or more positions in itsrotation. For example, if the plane of rotation is analogized to a clockface, the transmitters of a first blade may be activated when the bladeis at the 12 o'clock position and 6 o'clock positions, and thetransmitters may be deactivated when the blade is at the 3 o'clockposition and 9 o'clock positions. A second blade may have the oppositecycle and may activate at 3 o'clock and 9 o'clock and deactivate at 12o'clock and 6 o'clock. As discussed elsewhere one or more factors suchas the number of blades, speed of rotation, number of transmitters,number of blades having transmitters, migratory patterns, time of day,temperature or other weather conditions, and the like may be inputs tothe controller in determining a staggering scheme.

In some aspects, an input to the controller may be one or morecoefficients or equations calculated as part of a developed acousticmodel. According to the developed acoustical model, transmitters may beactivated or deactivated as a result of a determination of the requiredquantity and optimal array orientation to meet acoustic requirementslocal to one or more wind turbines. This may be, for example, based onthe species of bats documented by field research local to the windturbine, and determination as to the echolocation spectrum required tomitigate or eliminate wildlife encounters with the wind turbine.

Upon determination of an acoustical model applicable to one or more windturbines, controller instructions may be generated and transmitted tothe controller or controllers of the one or more wind turbines.Modification of the acoustical model may occur in response to feedbackor additional field-research.

Due to regulatory, manufacturing, and economic factors, hardware placedinto a wind turbine may be required to conform to standards such as theIEC 61400 standard, and transmitters and controllers may be selected ordesigned to comply with such standards. As another example, certainmanufacturers and operators of wind turbines may require that systemcomponents have an IP65 rating. An IP65 rating ensures that the systemdoes not allow dust ingress, and may be capable of withstanding waterspray from water jets for three minutes at 12.5 liters per minute, witha pressure of 30 kPa at a distance of 3 meters.

In FIG. 6, an exemplary block diagram of a controller 50, which may be acomputing device, is shown. The controller contains system bus 608,where a bus is a set of hardware lines used for data transfer among thecomponents of a computing device or processing system. Bus 608 isessentially a shared conduit that connects different elements of acontroller (e.g., processor, disk storage, memory, input/output ports,network ports, etc.) that enables the transfer of information betweenthe elements. Attached to system bus 608 is I/O device interface 610 forconnecting various input and output devices (e.g., keyboard, mouse,displays, printers, information sources, servers, computing devices,transmitters, etc.) to the controller. Network interface 612 allows thecomputing device to connect to various other devices attached to anetwork (not shown). Memory 614 provides volatile storage for computersoftware instructions 616 and data 618 used to implement aspectsdescribed herein (e.g. controlling transmission from one or moretransmitters to reduce or eliminate wildlife activity near a windturbine). Disk storage 620 provides non-volatile storage for computersoftware instructions 622 and data 624 used to implement various aspectsof the present disclosure. Central processor unit 626 is also attachedto system bus 608 and provides for the execution of computerinstructions.

In one aspect, the processor routines 616 and 622 as well as data 618and 624 are a computer program product, including a computer-readablemedium (e.g., a removable storage medium such as one or more DVD-ROM's,CD-ROM's, diskettes, tapes, etc.) that provides at least a portion ofthe software instructions for implementing aspects of the presentdisclosure. The computer program product can be installed by anysuitable software installation procedure, as is well known in the art.At least a portion of the software instructions may also be downloadedover a cable, communication and/or wireless connection.Computer-readable media include all computer-readable media but do notinclude transitory propagating signals.

One or more aspects may be embodied in computer-usable or readable dataand/or computer-executable instructions, such as in one or more programmodules, executed by one or more computers or other devices as describedherein. Generally, program modules include routines, programs, objects,components, data structures, etc. that perform particular tasks orimplement particular abstract data types when executed by a processor ina computer or other device. The modules may be written in a source codeprogramming language that is subsequently compiled for execution, or maybe written in a scripting language such as (but not limited to) HTML orXML. The computer executable instructions may be stored on a computerreadable medium such as a hard disk, optical disk, removable storagemedia, solid state memory, RAM, etc. As will be appreciated by one ofskill in the art, the functionality of the program modules may becombined or distributed as desired in various embodiments. In addition,the functionality may be embodied in whole or in part in firmware orhardware equivalents such as integrated circuits, field programmablegate arrays (FPGA), and the like. Particular data structures may be usedto more effectively implement one or more aspects, and such datastructures are contemplated within the scope of computer executableinstructions and computer-usable data described herein.

While aspects have been particularly shown and described with referencesto example embodiments thereof, it will be understood that variouschanges in form and details may be made therein without departing fromthe scope and spirit identified by the appended claims.

What is claimed is:
 1. A wind turbine blade comprising: a plurality ofsockets; and a plurality of acoustical transmitters arranged in thesockets configured to transmit an acoustic signal comprising one or morefrequencies.
 2. The wind turbine blade of claim 1, wherein eachacoustical transmitter in the plurality of acoustical transmitters isconfigured to transmit a signal comprising an ultrasonic frequency. 3.The wind turbine blade of claim 2, wherein the ultrasonic frequency isin a range from 20 kilohertz to 125 kilohertz.
 4. The wind turbine bladeof claim 1, wherein a first set of acoustical transmitters in theplurality of acoustical transmitters is configured to transmit a signalcomprising a first ultrasonic frequency, and wherein a second set ofacoustical transmitters in the plurality of acoustical transmitters isconfigured to transmit a signal comprising a second ultrasonic frequencydifferent from the first ultrasonic frequency.
 5. The wind turbine bladeof claim 1, wherein the acoustical transmitters are mounted in thesockets via a bayonet coupling.
 6. The wind turbine blade of claim 1,further comprising: a controller configured to control acoustictransmissions of the acoustical transmitters.
 7. A method comprising:controlling, by a computing device, a plurality of acousticaltransmitters arranged on blades of a wind turbine, wherein controllingthe plurality of acoustical transmitters comprises enabling thetransmitters for a first period of time and disabling the transmittersfor a second period of time.
 8. The method of claim 7, whereincontrolling the plurality of acoustical transmitters further comprisesdirecting the plurality of acoustical transmitter to output a firstsignal comprising a first frequency during the first period of time. 9.The method of claim 8, wherein controlling the plurality of acousticaltransmitters further comprises enabling the transmitters for a thirdperiod of time and directing the plurality of acoustical transmitter tooutput a second signal comprising a second frequency different from thefirst frequency during the third period of time.
 10. The method of claim8, wherein the first frequency is a frequency in a range from 15 kHz to125 kHz.
 11. The method of claim 8, wherein the first frequency is anultrasonic frequency.
 12. The method of claim 8, wherein an acousticaltransmitter in the plurality of acoustical transmitters is inserted in asocket arranged on a blade of the wind turbine.
 13. The method of claim8, wherein a first acoustical transmitter in the plurality of acousticaltransmitters is arranged on a first blade of the wind turbine, and asecond acoustical transmitter in the plurality of acousticaltransmitters is arranged on a second blade of the wind turbine.
 14. Themethod of claim 8, further comprising: transmitting a controlinstruction to the controller, said control instruction comprising anindication of the first frequency.
 15. The method of claim 7, whereincontrolling the plurality of acoustical transmitters further comprisesdirecting a first set of acoustical transmitters from the plurality ofacoustical transmitters to output a signal comprising a first frequency,and directing a second set of acoustical transmitters from the pluralityof acoustical transmitters to output a signal comprising a secondfrequency.
 16. The method of claim 15, wherein the first set ofacoustical transmitters comprises different transmitters from the secondset of acoustical transmitters.
 17. A wind turbine system comprising: awind turbine comprising one or more blades, each blade comprising aplurality of sockets; a plurality of acoustical transmitters, wherein anumber of acoustical transmitters in the plurality of acousticaltransmitters is less than or equal to a number of sockets in theplurality of sockets, each acoustical transmitter in the plurality ofacoustical transmitters arranged in a subset of the plurality ofsockets; and a controller configured to control at least one controlledacoustical transmitter in the plurality of acoustical transmitters. 18.The system of claim 17, wherein the controller comprises a wirelesscontrol transmitter and the at least one controlled acousticaltransmitter comprises a wireless control receiver, the at least onecontrolled acoustical transmitter being controlled by the controllerthrough transmission of a control instruction from the controller viathe wireless control transmitter and the wireless control receiver. 19.The system of claim 17, wherein a pressure sensor is arranged in asocket not in the subset of the plurality of sockets.
 20. The system ofclaim 17, wherein the controlling the at least one controlled acousticaltransmitter comprises directing the at least one controlled acousticaltransmitter to output a signal comprising an ultrasonic frequency.